When you write : print_string texto^"Una dola\n"; you must put parenthesis around your string : print_string (texto^"Una dola\n"); Otherwise it means you concatenates a string with a thing of type unit. Esther 2010/12/15 sieira > > Why doesn't this work?: > > type menu = {Textos: string list; Claves:string list};; > > let menu_principal = {Textos = ["Clientes";"Operaciones"];Claves = > ["1";"2"]};; > let rec pinta_menu = function > {Textos = []; Claves = []} -> > begin > print_string ">"; > (); > end > | {Textos = _; Claves = []} -> > begin > print_string "[EE] Error en el menu"; > (); > end > | {Textos = []; Claves = _} -> > begin > print_string "[EE] Error en el menu"; > (); > end > | {Textos = texto::textos; Claves = clave::claves} -> > begin > print_string texto^"Una dola\n"; > pinta_menu({Textos = textos; Claves = claves}); > end;; > > > (Returns > > "This expression has type unit" > ) > > While this does: > > let rec pinta_menu = function > [],[] -> > begin > print_string ">"; > (); > end > | _,[] -> > begin > print_string "[EE] Error en el menu"; > (); > end > | [];_} -> > begin > print_string "[EE] Error en el menu"; > (); > end > | texto::textos;clave::claves -> > begin > print_string texto^"Una dola\n"; > pinta_menu({Textos = textos; Claves = claves}); > end;; > > pinta_menu(menu_principal);; > > > Note that Textos ean texts and Claves mean keys > > > pinta_menu(menu_principal);; > -- > View this message in context: > http://old.nabble.com/Doubt-about-function-delaration-parameter-tp30464033p30464033.html > Sent from the Caml Discuss mailing list archive at Nabble.com. > > _______________________________________________ > Caml-list mailing list. Subscription management: > http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list > Archives: http://caml.inria.fr > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners > Bug reports: http://caml.inria.fr/bin/caml-bugs >